"Shaking off those leftovers like..." Timberlake, 36, captioned a clip of himself cranking out an impressive number of pushups with son Silas, 2, perched on his back. "Hope everyone had a great Thanksgiving!"

Timberlake also gave a shout-out to wife Jessica Biel, 35, whose shadow can be seen on camera duty.

Can we take a moment to admire the head of hair on Silas? His luscious waves take us back the early days of Timber-cise ... a workout that then took place on puppet strings.